CVE-2026-5423 Vulnerability Analysis & Exploit Details

CVE-2026-5423 Vulnerability Summary

CVE-2026-5423: @neo4j/graphql library versions prior to 7.5.6 fail to verify the authenticity of a client-supplied, pre-decoded JWT object passed through GraphQL subscription connectionParams. As a result, any unauthenticated remote client that can open a GraphQL-over-WebSocket connection can forge arbitrary JWT claims (e.g. sub, roles) in connectionParams.jwt and have them accepted as authenticated identity for the purposes of @authentication and @subscriptionsAuthorization directive evaluation. This allows a fully unauthenticated attacker to receive subscription events that should be restricted to specific authenticated roles/users. Upgrade the library to versions 7.5.6+ or 5.12.14+. v6 is end-of-life and will not receive a fix.

CVE-2026-5423 References

External References

• https://github.com/neo4j/graphql/security/advisories/GHSA-fcpg-3fw5-vc65
• https://neo4j.com/security/CVE-2026-5423

CWE Common Weakness Enumeration

CAPEC Common Attack Pattern Enumeration and Classification

• Buffer Overflow via Environment Variables CAPEC-10 This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the adversary finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
• Subverting Environment Variable Values CAPEC-13 The adversary directly or indirectly modifies environment variables used by or controlling the target software. The adversary's goal is to cause the target software to deviate from its expected operation in a manner that benefits the adversary.
• Exploitation of Trusted Identifiers CAPEC-21 An adversary guesses, obtains, or "rides" a trusted identifier (e.g. session ID, resource ID, cookie, etc.) to perform authorized actions under the guise of an authenticated user or service.
• HTTP Verb Tampering CAPEC-274 An attacker modifies the HTTP Verb (e.g. GET, PUT, TRACE, etc.) in order to bypass access restrictions. Some web environments allow administrators to restrict access based on the HTTP Verb used with requests. However, attackers can often provide a different HTTP Verb, or even provide a random string as a verb in order to bypass these protections. This allows the attacker to access data that should otherwise be protected.
• Accessing/Intercepting/Modifying HTTP Cookies CAPEC-31 This attack relies on the use of HTTP Cookies to store credentials, state information and other critical data on client systems. There are several different forms of this attack. The first form of this attack involves accessing HTTP Cookies to mine for potentially sensitive data contained therein. The second form involves intercepting this data as it is transmitted from client to server. This intercepted information is then used by the adversary to impersonate the remote user/session. The third form is when the cookie's content is modified by the adversary before it is sent back to the server. Here the adversary seeks to convince the target server to operate on this falsified information.
• Manipulating Opaque Client-based Data Tokens CAPEC-39 In circumstances where an application holds important data client-side in tokens (cookies, URLs, data files, and so forth) that data can be manipulated. If client or server-side application components reinterpret that data as authentication tokens or data (such as store item pricing or wallet information) then even opaquely manipulating that data may bear fruit for an Attacker. In this pattern an attacker undermines the assumption that client side tokens have been adequately protected from tampering through use of encryption or obfuscation.
• Buffer Overflow via Symbolic Links CAPEC-45 This type of attack leverages the use of symbolic links to cause buffer overflows. An adversary can try to create or manipulate a symbolic link file such that its contents result in out of bounds data. When the target software processes the symbolic link file, it could potentially overflow internal buffers with insufficient bounds checking.
• Manipulating User-Controlled Variables CAPEC-77 This attack targets user controlled variables (DEBUG=1, PHP Globals, and So Forth). An adversary can override variables leveraging user-supplied, untrusted query variables directly used on the application server without any data sanitization. In extreme cases, the adversary can change variables controlling the business logic of the application. For instance, in languages like PHP, a number of poorly set default configurations may allow the user to override variables.

Other 5 Recently Published CVEs Vulnerabilities

• CVE-2026-90555 – vLLM versions before 0.28.0 fail to validate audio sample rate headers in the transcription endpoint, allowing authenticated clients to bypass dura...
• CVE-2026-90554 – vLLM versions >=0.10.2 and <0.28.0 do not apply any audio decode-size or duration limit when extracting audio from video input for NanoNemotronVL m...
• CVE-2026-90553 – vLLM before 0.28.0 contains a remote code execution vulnerability in the LlavaOnevision2 processor loader that ignores the trust_remote_code parame...
• CVE-2026-90552 – WWBN AVideo through commit c3edcc274c389816d434acadac07ee78eaf330c1 fails to validate playlist ownership in the Playlists_schedules/list.json.php a...
• CVE-2026-90551 – WWBN AVideo through commit c3edcc274c389816d434acadac07ee78eaf330c1 fails to validate playlist ownership in the video_from_program API endpoint, al...